CVEvulnerability

CVE-2026-45352

7.5 HIGH Published 2026-05-29 Modified 2026-07-22 Official page ↗
Status
Modified
Published
2026-05-29
Last modified
2026-07-22
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-1285, CWE-20, CWE-770

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding causes unbounded memory allocation and process crash. The ChunkedDecoder::read_payload function in cpp-httplib (httplib.h) parses the chunk-size field of HTTP chunked transfer encoding using std::strtoul(). Per the C standard (§7.22.1.4), strtoul silently accepts a leading minus sign, performing unsigned wrap-around: strtoul("-2", …, 16) returns ULONG_MAX − 1 (0xFFFFFFFFFFFFFFFE). The library's only guard (line 12833) rejects ULONG_MAX (the result of "-1"), but any other negative value such as "-2" passes validation. The resulting near-maximum value is stored in chunk_remaining and controls how many bytes the server's read loop consumes from the network. This vulnerability is fixed in 0.43.4.

Affected configurations

• yhirose cpp-httplib (< 0.43.4)

Related

Weakness · CWE (3)

  • CWE-1285 Improper Validation of Specified Index, Position, or Offset in Input weakness
  • CWE-20 Improper Input Validation weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling weakness

References